To provide cellular wireless communication service, a wireless service provider typically employs an access network that functions to connect one or more access terminals (e.g., cell phones, PDAs, laptops, netbooks, tablets, and/or other wirelessly-equipped devices) with one or more transport networks. In a typical access network, an area is divided geographically into a number of coverage areas, such as cells and sectors, each defined by a radio frequency (RF) radiation pattern from a respective base transceiver station (BTS). Within each coverage area, the BTS's RF radiation pattern may provide one or more wireless links, each on a carrier (or set of carriers), over which access terminals may communicate with the access network. In turn, the access network may provide connectivity with the public switched telephone network (PSTN), the Internet, and/or other transport networks.
The wireless links may carry communications between the access network and the access terminals according to any of a variety of wireless protocols. Depending on the protocol employed, each wireless link may also be divided into a plurality of channels for carrying communications between the access network and the access terminals. For example, each wireless link may include a plurality of forward-link channels, such as forward traffic channels, for carrying communications from the access network to the access terminals. As another example, each wireless link may include a plurality of reverse-link channels, such as reverse traffic channels, for carrying communications from the access terminals to the access network.
In many wireless protocols, the access network and active access terminals (i.e., access terminals with an assigned traffic channel) may engage in a power-control process to control transmission power for communications over the wireless links provided by the access network. In particular, the access network and an active access terminal may engage in a reverse power-control process to control the reverse transmission power at which the access terminal sends data on an established reverse traffic channel of a wireless link provided by the access network. Similarly, an active access terminal and the access network may engage in a forward power-control process to control the forward transmission power at which the access network sends data on an established forward traffic channel of a wireless link provided by the access network.
In an example power-control process, a power-controlling entity may regularly determine a channel quality at which a given wireless link is carrying a given communication session with the power-controlled entity. The power-controlling entity may then regularly compare the determined quality to a threshold quality and thereby decide whether to send a “power up” power control command (PCC) that instructs the power-controlled entity to increase its transmission power by a given increment value (e.g., 1 dB) for the given communication session on the given wireless link or a “power down” PCC that instructs the power-controlled entity to decrease its transmission power by a given decrement value (e.g., 1 dB) for the given communication session on the given wireless link. For instance, based on each comparison, the power-controlling entity may decide to send (a) a “power up” PCC directed to power-controlled entity if the determined quality is less than the threshold quality (which indicates that the power-controlling entity is detecting a lower quality) or (b) a “power down” PCC directed to power-controlled entity if the determined quality is greater than the threshold quality (which indicates that the power-controlling entity is detecting a higher quality). Accordingly, the power-controlling entity may send a series of PCCs directed to the power-controlled entity on the given wireless link.
As the power-controlling entity sends the series of PCCs directed to the power-controlled entity on the given wireless link, the power-controlled entity may receive the series of PCCs from the power-controlling entity. In response to each PCC received from the power-controlling entity, the power-controlled entity may then responsively adjust its transmission power for the given communication session on the given wireless link in accordance with the PCC. For instance, the power-controlled entity may increase its transmission power for the given communication session on the given wireless link in response to receiving a “power up” PCC from the power-controlling entity. And the power-controlled entity may decrease its transmission power for the given communication session on the given wireless link in response to receiving a “power down” PCC from the power-controlling entity. Accordingly, during this power-control process, the power-controlled entity may continually adjust its transmission power for the given communication session on the given wireless link.
Advantageously, such a power-control process may enable the access network and active access terminals to balance between maintaining an acceptable strength of a traffic-channel communication and preventing the traffic-channel communication from becoming overly strong and unduly interfering with other communications.